{"doi":"10.3389/fnmol.2022.1017404","title":"Analyzing the mechanisms that facilitate the subtype-specific assembly of γ-aminobutyric acid type A receptors","abstract":"Impaired inhibitory signaling underlies the pathophysiology of many neuropsychiatric and neurodevelopmental disorders including autism spectrum disorders and epilepsy. Neuronal inhibition is regulated by synaptic and extrasynaptic γ -aminobutyric acid type A receptors (GABA A Rs), which mediate phasic and tonic inhibition, respectively. These two GABA A R subtypes differ in their function, ligand sensitivity, and physiological properties. Importantly, they contain different α subunit isoforms: synaptic GABA A Rs contain the α1–3 subunits whereas extrasynaptic GABA A Rs contain the α4–6 subunits. While the subunit composition is critical for the distinct roles of synaptic and extrasynaptic GABA A R subtypes in inhibition, the molecular mechanism of the subtype-specific assembly has not been elucidated. To address this issue, we purified endogenous α1- and α4-containing GABA A Rs from adult murine forebrains and examined their subunit composition and interacting proteins using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and quantitative analysis. We found that the α1 and α4 subunits form separate populations of GABA A Rs and interact with distinct sets of binding proteins. We also discovered that the β3 subunit, which co-purifies with both the α1 and α4 subunits, has different levels of phosphorylation on serines 408 and 409 (S408/9) between the two receptor subtypes. To understand the role S408/9 plays in the assembly of α1- and α4-containing GABA A Rs, we examined the effects of S408/9A (alanine) knock-in mutation on the subunit composition of the two receptor subtypes using LC-MS/MS and quantitative analysis. We discovered that the S408/9A mutation results in the formation of novel α1α4-containing GABA A Rs. Moreover, in S408/9A mutants, the plasma membrane expression of the α4 subunit is increased whereas its retention in the endoplasmic reticulum is reduced. These findings suggest that S408/9 play a critical role in determining the subtype-specific assembly of GABA A Rs, and thus the efficacy of neuronal inhibition.","journal":"Frontiers in Molecular Neuroscience","year":2022,"id":265367,"datarank":0.4392641346204494,"base_score":2.4849066497880004,"endowment":2.4849066497880004,"self_citation_contribution":0.37273599746820013,"citation_network_contribution":0.06652813715224926,"self_endowment_contribution":0.37273599746820013,"citer_contribution":0.06652813715224926,"corpus_percentile":null,"corpus_rank":null,"citation_count":11,"citer_count":5,"citers_with_citation_signal":3,"citers_with_endowment":3,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9588,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2022-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":401616,"name":"Joshua L. Smalley","orcid":"0000-0002-7437-6655","position":1,"is_corresponding":false},{"id":233442,"name":"Abigail Lemons","orcid":"0000-0002-9431-0573","position":2,"is_corresponding":false},{"id":486741,"name":"Qiu Ren","orcid":"0000-0003-4371-6298","position":3,"is_corresponding":false},{"id":487648,"name":"Christopher E. Bope","orcid":null,"position":4,"is_corresponding":false},{"id":718633,"name":"Jake S. Dengler","orcid":null,"position":5,"is_corresponding":false},{"id":486745,"name":"Paul Davies","orcid":"0000-0002-3973-3143","position":6,"is_corresponding":false},{"id":368750,"name":"Stephen J. Moss","orcid":"0000-0001-7459-3644","position":7,"is_corresponding":false},{"id":486740,"name":"Catherine Choi","orcid":"0000-0002-3215-9601","position":0,"is_corresponding":true}],"reference_count":76,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T00:26:45.905331Z","pmid":"36263376","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}